What Nature demands, Nature shall receive
by Elialys
Summary: 'When the time comes, in order for balance to be completely restored, what was once taken must be returned.' Aren't all the best love stories tragedies? Especially when He's from one Universe and She's from another.


**Disclaimer**: Still don't own Fringe. If I did, I would certainly not end the show like I do in this story.

**Spoilers:** Up to 3x09 'Marionette'.

**Rating:** T, definitely T.

**A/N**: So here's yet another oneshot (and one day, I will write oneshots that are not 10 pages long, I will). Because my muse just loves to give me crazy ideas at 2am. And this is sort of a 'potential End of the Show' theory.

What if, in order to restore the balance between the two Universes, Peter had to go back to his Side? Forever…and ever. Yes, I thought about it when I started to think about the similarities between Fringe and the series '_His Dark Materials_' (awesome books by Philip Pullman).

So yep, that's all I had to work with, there is no real, clever plot behind this. Just an intense, masochistic need to make myself cry again writing some Polivia!angst!doom (and I succeeded beyond expectation).

You are warned, this is NOT a fluffy story.

Also, rated T because of a mild sex-scene.

See you on the other side *sobs*

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**WHAT NATURE DEMANDS, NATURE SHALL RECEIVE  
**

* * *

It's unexpected, like it always seems to be. Walter's sudden recovery of some lost memory, that is. And the memory itself is quite… brutal.

Walter is so distressed that it takes them more than fifteen minutes to actually understand what he's babbling about, between his raged outbursts and heartbroken sobs. Half the things that was up on a surface of some sort is now on the ground; Astrid tries three different vinyl before she gives up, just as confused and worried as Peter and Olivia.

What can possibly be _that_ bad? They have just saved both Universes a few days ago, after all, and they all made it out alive, which is a miracle in itself. They should still be busy celebrating.

It takes Peter firm hands on Walter's wet cheeks and his gaze intensely focused on his for his father to actually calm down enough to make himself clear.

"I…I remember, Peter, I remember," he stammers, grabbing his shirt so tightly that his knuckles turn white.

"Remember _what_, Walter?" He asks as calmly as possible.

"What _he_ told me." Walter almost moans. "He gave me so many…so many messages, and I just didn't want to remember this one."

"Care to share with us?" Peter asks softly, calm blue eyes staring into watery blue eyes.

"_When the time comes, in order for balance to be completely restored, what was once taken must be returned."_

And before Peter can even start to decrypt the message, Walter moves away from him, throwing himself into a monologue about how this means that Peter must go back to the Other Side and stay there permanently, because everything needs to go back where it belongs.

That is when Olivia reacts.

And he stares at her, mesmerized, as she goes through all the stages of grief within a short half an hour.

It goes from her frozen half-smile to a very angry pacing, hands on her hips, before the pacing gets quite desperate and her hair takes a toll as she grabs it.

Peter, on the other hand, doesn't say anything, doesn't even move. As always, the numbness is back, that damn _numbness_ that takes every feeling from him and leaves him blank, while others –like Walter and Olivia- are losing it.

And the color of her face changes, too, as she goes through all this amazing range of emotions.

"What do you mean 'permanently'? Half-smile, pale cheeks.

"What do you mean, 'no more cross-overs', you are _not_ seriously suggesting that I should just let this happen, are you?" Blazing eyes, flushed cheeks.

"No, there must be another way, Walter. You need to find another way." Eyes wide, almost begging, skin now grayish.

"This is not happening." And there is that heartbroken look of hers again, her face too pale, way too pale.

And the funniest thing of all is that through all this, she doesn't even look at him. She stares at Walter, and shares desperate looks with a speechless Astrid, but she doesn't look at _him_, despite the fact that he's the center of the discussion, the reason of her distress.

What's also funny is that Peter thinks it is ridiculous, all of this. They have _really_ saved both worlds, a few days ago. And above all, Olivia is finally all his, for good, for _real_, and they were quite enjoying this short period of time during which nothing matters but each other and the delicious endorphins of love.

This, this is not happening.

Peter might also be going through the phases of grief, after all.

But all the denial in the world cannot make the reality disappear. And so he remains comfortably numb, while Olivia keeps on going through this rainbow of colors and emotions.

And it's all there again, a few hours later, in the darkness of her place. Anger, bargaining, depression. She pins him to the door as soon as it closes, and demands everything of him without a single word.

Who needs words when there is liquid fire throwing herself at you, really?

And he lets her take the lead for a while, because he's too stunned, and too broken, to do anything but _feel_, and he feels, he feels her, it's her, her, _her_, all of her and God he loves her.

She's mad, she's mad, she's _infuriated_, she hates the world and the Universes, and she lets him know with nails digging deep into the flesh of his back, legs locked around his, bringing him down hard, harder, and God she's everywhere and she's everything and this cannot be.

And as the wave keeps on rising and rising and rising, following the rhythms of their dance, the harsh sting of her nails in his back vanishes as her fingers slide into his hair. She brings his face closer to hers, and he's lost into the emerald of her eyes, so fucking haunted and gorgeous and _his_.

Skin against skin, soul into soul, he cannot bear the thought of _not_ being with her for each remaining minute of his life, and so he forgets himself as she calls out his name in hushed whispers and desperate pleas. And he cannot tell what is this wetness on their skins, sweat or tears, and who cares?

It's all over too soon, though, quivering, breathless mess in the middle of her bed, her fingers still in his hair, his face pressed against her neck. Because that's where he belongs, doesn't he? With their bodies still so tightly and desperately intertwined that he cannot tell where hers ends and his begins, loving her so fucking much that it's coming out of his pores.

And then she tenses, her hands leaving his hair to come push against his chest.

"Get off," she breathes out, and there is such a sense of panic in those two words that he obeys as fast as he can.

She immediately sits up and moves, and he's convinced that she's going to simply run away from him. But she stops at the edge of the bed and just…sits there, motionless. And he can't do anything but stare at her bare back, at her disheveled, beautiful hair, as she hugs herself.

Another long minute passes before she speaks. And when she does, he wishes she hadn't.

"Would you go to her, if she was still alive?"

He doesn't ask who she's talking about, because it's so obvious that she's talking about _her_.

Any other day that didn't include him having to leave his adoptive world and the other half of his soul behind, and he may have let out a bewildered chuckle and say '_What?'_ with his best frown.

Today is not the day, though. Anger stings hard instead. Anger and hurt, because everything hurts right now.

"How can you ask that?" he asks, and his voice is too tight, too tensed, too broken.

She shrugs softly, and some of her hair slides off her shoulder; he sees the shivers that shake her body, her skin still layered with sweat and goose-bumps. She's cold.

"Olivia." He says her name in such a low and furious voice that she startles a little. "I'm serious, how can you even think about _her_ right now?"

She turns her head to look at him, then. He expected to see a blank face, a distant, hurt look he has seen too many times before and hates with a passion. Her face isn't blank at all; it's constricted in such a painful way that he feels the hole that is forming itself within his chest.

"I'm not asking this out of some sick…jealousy," she whispers then, and she looks just as appalled by the fact that he'd thought that of her as he'd felt actually thinking it.

"Why, then?" He asks, his voice softer.

She smiles, and as always, he's amazed by her ability to smile when what she really wants to do is cry. Amazed and quite heartbroken.

"Because if there were another you Here, I'm not sure I wouldn't go looking for him, eventually."

And there is so much pain in this, so much truth too, as well as too much of what is to come, that his throat closes up, obstructed by a monstrous lump.

He wants to tell her that if there had been another him, _he _wouldn't be Here in the first place, he would have never been Here. He might have died as a child, because Walter would have never opened a door between the Universes to save him.

But most of all, they wouldn't be _here_, right now, in such unimaginable agony. So in love. But he wouldn't trade it for the worlds. He wouldn't trade those few years with her for the worlds.

He can't speak, but something must have shown on his face, because she comes back to him, then. She gently pushes him back on the mattress and lays her quivering body upon his; he wraps her in his arms, as she buries her face in the crook of his neck, breathing hard and loud, inhaling his scent.

They stay like this for an endless time, simply absorbing the feel of the other, because they know they can't take any of this for granted anymore. They stay like this until she raises her head to kiss his face. She kisses his jaw, his ear, his chin, his lips, and he cups her face in his hands. He ignores the wetness on her cheeks, kissing her deep and slow, until she grinds her hips against his, both of them ready again and yet, they know they will never be ready.

But if this really is their last night, they will take what they can, while they can.

They'll take it all.

...

The harsh and unbearable sound of sobs resonates through the lab.

'_I just want more time,'_ is all Olivia can think.

The sobs are loud and made of sheer heartbreak. There is no holding back, no trying to muffle them.

Walter never was one to hold his emotions back, and today's no different. He was doing surprisingly well for a while, though, despite the endless flow of silent tears rolling out of his eyes, as he explained about the Soft Spot they will need to go to, then shared some mindless small talk with the son he will never see again after today.

And then there is a lot of '_Remember when…?_'

Peter remembers it all, and he smiles warmly at his father as they share anecdotes.

'_I just want more time.'_

Olivia stands leaning against a wall, arms crossed, quiet and absolutely numb, staring at them with dead eyes. She has reached that point where it hurts so much that everything else seems to become insignificant compared to the pain, everything becomes dull and unimportant. She stares at those atrocious goodbyes, and doesn't feel a thing.

"Remember your lucky silver dollar?"

Fuck the silver dollar. '_I just want more time.'_

Peter smiles. He smiles and pulls that same silver dollar out of his pocket, quickly passing it from finger to finger, and Walter beams, his wet face illuminating at the sight. And then Peter holds the silver dollar out for his father to take and says:

"I want you to have it."

Walter's face crumbles as he stares at the shiny dollar. "Peter…"

"It's okay, dad," he says softly. "Take it as a token of my gratitude, for saving my life so many times. I really appreciate it."

That's when the sobbing start, and never seems to end. Walter clings to his son, and Peter lets him, embracing him in a tight hug, eyes closed, nose buried in his grey hair. When he opens his eyes, he holds out one of his arms to let an Astrid very much in tears herself join the group hug. His gaze is not on Astrid, though.

It's on Olivia. And she stares back, unmoving, almost unfeeling. But that's not true, of course.

She feels so much, and it hurts so _deep_, that she feels like throwing up. She can't do this, share stupid anecdotes and tears and comfort.

He understands that, and he tells her with his eyes, blue boring into green, no trace of a smile left on his lips.

'_I just want more time, too.'_

...

It takes Peter and Olivia two hours to reach the Soft Spot indicated by Walter.

As he has explained too many times, trying and failing to find another way, the Worlds are now quickly healing themselves after what they did with the Machine, which basically means that all the Soft Spots are going to disappear within the next few weeks.

It also explains why Peter has to leave so quickly. It would be a shame if he ended up stuck Here, wouldn't it?

The thought is bitter, as is everything else going through Olivia's head as she drives them in silence. This is not his decision, this is not his choice. This is for the sake of the worlds they have both sworn to protect and save.

It doesn't help. Nothing can help her go through this. Nothing but herself, once again.

That's why she makes sure to stay strong and composed, despite the fact that her insides feel like they're quickly being dissolved in acid, every mile bringing them closer to the end.

This is destroying her, but she will not be weak.

So they drive in silence, because there is nothing to say, nothing that can make them feel better. They don't do any '_Remember when I drank worms and you thought it was hilarious?'_; they don't declare their endless love to each other, and they don't promise to go to the same spot every year just to '_feel the other on the Other Side_.'

Clichés have always been too clichés for them.

They reach the woods as the day starts to dim; it could have been a beautiful sunset, but it is not, another cliché they ignore. The sky is cloudy and grey, which is actually perfect because that's exactly how she feels.

She doesn't even look up at him, as she wraps her arms around his middle to embrace him, because that's how they've been crossing-over together in the past. She has become quite the pro, especially when she does it with Peter. Her abilities have always been so much stronger when she's surrounded by his warmth.

But she can't think about it. This is useless, _pointless_, since she won't need her abilities anymore after today; and above all, he won't be here to help her shine.

Despite her determination to focus on everything else but him, not looking into his eyes isn't enough to prevent all of her senses from being attacked by _him_. The feel of his body against hers, as he holds her just a little too tight, and yet not close enough. The fast beat of his heart against her ears, his scent invading her lungs every time she breathes in.

She feels it all and stares at the trees to keep the tears from filling up her eyes.

Maybe they can just stay here. Get lost into the woods and never come out. Nobody would have to know. One little difference in the balance can't be _that_ bad, can it? One tiny breach would not be enough for the worlds to start disintegrating again; Peter is just one person among twelve billions, after all.

He's one among billions.

So why does she need _him_ so much?

"Olivia?" he prods her softly, because they've been standing there in this embrace for several minutes now, and they're clearly still on the same Side.

She closes her eyes then, and allows herself to be completely swallowed by the fury of emotions constantly swirling within her. She lets her helplessness and her fear take over, and just like that, the worlds shifts beneath their feet and all around them.

She gets away from him as soon as the air feels steady again, stumbling a little as she puts a reasonable distance between them. Crossing-over never was easy on her, and she knows she's going to be incredibly weak for days after she crosses-over a second time.

Not that it matters very much.

For a fleeting second, she almost considers the idea of going back _now_, while she's still fully 'activated', and most of all heartbroken. It would be easier, wouldn't it? To just leave without a word, without a look, because every word, every look will just remind her that they are the very last she will ever share with him.

But she can't leave like this, of course. For one thing, he's decided on not letting her get away from him, judging by the way he walks to her decidedly, despite the fact that she's _clearly _trying to stay away.

He grabs her face in his hands to stop her from moving, forcing her to look up. His jaw is set and his eyes are dark.

"Damn it, 'Livia, I don't give a damn about you needing to keep that strong face on," he says, sounding and looking pissed off; but it all melts away as they stare at each other, and she sees her own despair reflecting in his eyes.

He swallows hard, bowing his head until his face reaches hers, foreheads and noses touching; she grabs his coat, closing her eyes, her heart pounding furiously.

"I need to keep that face on, or I'll never leave you," she whispers, fighting again and fighting so hard to keep the pain away, to keep it inside, to keep it from bursting out of her and make her beg for _more time_. "I have to be strong."

His fingers on her face are holding on too tight, and it hurts, but she doesn't care, because it means he's still _there_ with her.

And so she pushes herself up, until their lips meet, quite desperately. She pours everything she cannot say into this kiss, and so does he. It's slow and rushed, full of need and despair, of confusion and anger.

Must mostly, it's full of heartbreak.

And while kissing him has always managed to ignite desire from deep inside of her in the past, the only thing growing at that instant is the lump in her throat, and she knows everything that is contained in that lump, and she cannot let it out.

She lets go of his coat then and pushes him away once more, breathing hard. "Go," she orders him in a hoarse voice, and again, she cannot look in his eyes anymore, staring at his feet instead. He doesn't move, and she closes her eyes. "Please, Peter. If you love me, _go_ and don't look back."

She focuses on the sound of her own pounding heart against her ears, on her breathing, forcing herself to breathe deeply and steadily, and she waits. She waits for what seems to be an hour before she hears him move.

He moves away from her.

She opens her eyes when she can't hear his footsteps anymore. He hasn't gotten that far yet, only a few yards, but it's already too much. True to her request, he's not looking back; head bowed, he's simply…walking away.

And part of her wants so much for him to turn around and look at her, despite the fact that she's asked him not to. _Turn around turn around turn around turn around,_ is all her mind keeps on screaming.

But he doesn't turn around, because he loves her and she's asked him not to.

How many times has she looked at his back like this, as they were walking together to a crime scene, both in their peacoats? She stares at his coat more than anything else at that instant, because it is such an important part of him, in little ways she cannot explain. Dozens of images flash before her eyes, images of him, of him and her; but one imposes itself, as she remembers him standing in her living room in that very same coat, smiling at her softly, warmly, _lovingly_ even. She remembers feeling incredibly distressed at that moment, because she needed to tell him the truth about his origins, and yet she couldn't bring herself to do it.

She hadn't been able to do it because she had known even then just how badly she needed him; she had known she wouldn't be able to bear the sight of him walking away from her without a single glance back.

And just like that, something enormous breaks inside of her, as she realizes that she _is_ losing him. This is not some temporary separation; this is not him leaving because he's hurt, or her staying away because she feels betrayed.

This is the Universes standing up between them, never allowing them another _second_ together again.

She is losing him, and all strength is drained out of her as she feels her whole world shattering and she loses herself to the pain.

And this is the last image she will ever have of him.

Him walking away.

"Peter!"

She didn't mean for her voice to sound so terrified and _loud_, but it does. She cries out his name as if she had just been stabbed in the heart, pain and despair ringing in the air. He turns around of course, his face distorted with worry and fear for her, surely imagining the worst scenarios as he thought she was about to cross-over.

But she's fine, really, she's fine. Except that she is everything but fine, and he knows it, already making his way back to her as she literally starts running.

She doesn't know who reaches the other first, and it doesn't matter. Their bodies collide hard and she clings to him desperately, pressing her face against his neck as heart-wrenching sobs break out of her, shaking her whole being to the core. Nothing's coherent, nothing feels real but _him_, and she hears his voice over her sobs, repeating the same words over and over '_I love you, I love you, I love you_,'; in her own head, the only words echoing there are '_ohgodpleasepleaseplease…ohgodpleasepleasePLEASE_'

This hurts too much, this cannot be; she cannot leave, because she cannot _live_ without him. She had sworn to herself a long time ago that she will never, ever become one of those women who claim they can't go on without a man in their lives; she had judged those women, almost disgusted by their weakness, and she had promised herself never to allow this to happen to her.

But she understands, now, she _understands_.

It's not about being weak and submissive. It's not about giving up her power to let him direct her life. It's all about finding strength in his eyes when she feels like giving up, it's all about searching comfort in his touch when she feels like curling up on the floor and letting the world beat her down, it's all about letting herself be immersed in his love, because she is beautiful and strong and perfect in his eyes, even if she will never be to herself or to others.

It's what this is all about, this endless source of comfort and love and belonging. That is why people say they cannot live without one another, because once you have experienced this, this unity of the souls, you cannot go back to being alone.

She understands now, but it's too late.

The choice is not theirs. It never was.

And so she sobs against him because there's nothing else she can do; she's about to lose him, and she cannot breathe.

She reaches up for his face, hands on his cheeks, and when she feels the wetness there beneath her fingers, she raises her head to look at him. She realizes then that she had never seen him cry before, and unbelievably, her heart breaks even more.

"I'm sorry," she chokes, and he mimics her, cupping her face with both his hands.

"For what?" he asks, and his voice is full of tears and she cannot bear it and all she wants to do is kiss his face again and again, kiss the salty drops away, mend his broken heart.

"For being so stupid, for wasting so much time," she manages to articulate between two broken sobs.

His hold on her cheeks tightens again, and he stares hard at her. "Don't do that, Olivia." His voice is low and furious again. "Do _not_ blame yourself, I forbid you to even _think _it."

To both their surprise, she lets a sound that is pretty close to a chuckle then. "I've never taken that kind of orders very well."

He kisses her forehead then, and she closes her eyes, as he lets go of her face to wrap his arms around her; she does the same, burying her face into the crook of his neck, that spot she could never get enough of, and they just hold onto each other tight, _tighter_, as tight as they can.

"I can't ask you not to agonize over this, Olivia," he whispers in her ears, "because I don't even know how _I _am going to survive this." She tries to keep the tears in, she really does; she just can't. "But I know it will be… 'easier', if I'm not constantly worrying about you beating yourself up over this, because it is _not_ your fault. It was never your fault."

She looks at him again then, with desperate, pleading eyes. "Peter," she whispers. "I'm scared."

She's not scared, she's _petrified_. She's terrified of having to go on without him, of forgetting the small details, of slowly moving on, because as much as she's hurting right now, that is what time does to you, and she doesn't want for him to become nothing but a memory, a ghost from her past.

True to himself, he cups her cheek in his hand again and offers her the softest smile, shaking his head. "Don't be."

They don't kiss. Instead, their foreheads come together again, noses touching, eyes boring into each other's soul, and it feels more intimate than any kiss they have ever shared.

"Do you remember what I told you, just before you went into the Tank for the very first time?" He whispers then. "What I told you about John?"

It doesn't take long for the distant memory to come back. She nods almost imperceptibly. "You said…You said '_I hope your guy is worth it_.'"

She feels his fingers on her face, his thumb gently brushing the wet skin of her cheek. "You were so stubborn, almost reckless. But always so brave; I think I might have loved you right then. I just never imagined that one day, you would show just as much courage and determination to save _me_."

"Peter," she chokes, wanting so badly to tell him that she doesn't regret anything; she doesn't regret crossing-over to go get him, despite everything that resulted. She would do it all over again in her heartbeat. But he stops her by gently running his thumb over her lips.

"I just wanted to thank you." He says softly. "I never thought someone would ever love me that much. And I have to believe that this, having to live without you, is worth it. That we're doing it for the sake of both our Worlds. And I need you to believe in this, too, to believe in this like you believed in John, like you believed in me."

She kisses his thumb softly. "I love you," is all she says, before she drops her head, her forehead resting against his chest as he buries his fingers into her hair. "I love you. I love you."

"I love you, too," he whispers back. "Now…go."

Olivia never was one to take orders from anybody. But Peter never was 'anybody' either.

And so she lets herself slip away from his embrace, leaving his scent, leaving his body warmth, leaving the feel of his hands in her hair, and soon, leaving his world altogether.

But as she does so, she stares into his eyes, and he stares back. And she can hear his unspoken words.

'_Believe in this like you believed in me.'_

And she knows she will.

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X_X **FIN **X_X

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**A/N**: Uhm…reviews? Nutella? Anyone? :D


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